The gurney in the execution chamber at the Oklahoma State Penitentiary.

Oklahoma Execution: What Went Wrong and What Happens Now?

By Tracy Connor

The execution of Clayton Lockett in Oklahoma began against a backdrop of controversy, with death-row inmates across the country challenging states' last-minute changes to lethal injections and the secrecy that shrouds drug suppliers.

It ended as a nightmare for everyone involved, with the convicted murderer appearing to regain consciousness and struggling to sit up, prison officials halting the execution, and Lockett then dying of a massive heart attack.

Here's a look at what happened at the Oklahoma State Penitentiary on Tuesday night and some of the history behind it:

What went wrong?

It's not entirely clear. The prison director said an intravenous line blew after Lockett was given midazolam, a sedative, and while two other drugs — the paralytic vecuronium bromide and the heart-stopper potassium chloride — were flowing into his body.

Vein problems are not unheard of during executions, but Lockett's appeals team says his veins were perfectly healthy. They suspect there was something wrong with the drugs or the way they were administered.

Lockett's lawyers say the injection was "experimental." Is that true?

The three-drug combination had been used in Florida, but never in Oklahoma. And Oklahoma chose a different dosage of midazolam, a common sedative known by the brand name Versed, so it's accurate to say the exact formula used Tuesday night had not been tested.

Before the execution, Lockett's lawyers tried to force prison officials to reveal where they obtained the lethal dose, saying they should be allowed to investigate how they were prepared and whether they would be effective, but the state' Supreme Court ultimately ruled against them.

Some pharmaceutical companies have refused to sell their products for capital punishment, forcing prisons to turn to less-regulated compounding pharmacies for specially mixed injections. In the wake of bad publicity and legal hassles, some pharmacies have gotten out of the business, too.

States are trying to keep the supply lines open by giving their drug connections anonymity, but defense lawyers contend the secrecy prevents them from investigating whether the injections would violate the constitutional protection against cruel and unusual punishment.

Is Lockett's execution the first one to go wrong?

At least two recent executions using new cocktails have drawn scrutiny because of complications.

When Michael Lee Wilson, 38, was put to death in January in Oklahoma for the murder of a store clerk, he reportedly blurted out, "My whole body is burning," after the pentobarbital was injected.

What happens now?

Oklahoma Gov. Mary Fallin — who last week accused the state Supreme Court of overstepping its bounds by putting Lockett's execution on temporary hold — tapped her public safety commissioner to lead a review of his death.

His lawyers are calling for an independent autopsy and the names of the drug sources.

The man who was scheduled to die two hours after Lockett, Charles Warner, received at least a 14-day reprieve.

Nationally, death-row inmates continue to challenge changes to execution protocols and laws and policies that keep the suppliers a secret.

Lawmakers in some death-penalty states are also pushing to have other forms of execution — such as firing squad or electric chair — reinstated. Experts on both sides of the debate say it's unlikely that will come to pass on a broad scale because the public is unlikely to embrace non-medical executions.

Some death-penalty foes are predicting the high-profile Lockett disaster — in the wake of publicity about reversed convictions — could erode American support for the death penalty.

Three weeks ago, the justices declined to take up the case of Christopher Sepulvado, who was sentenced to death for killing his 6-year-old stepson and challenged Louisiana's secrecy rules.

First published April 30 2014, 8:52 AM

Tracy Connor

Tracy Connor is a senior writer for NBC News. She started this role in December, 2012. Connor is responsible for reporting and writing breaking news, features and enterprise stories for NBCNews.com. Connor joined NBC News from the New York Daily News, where she was a senior writer covering a broad range of news and supervising the health and immigration beats. Prior to that she was an assistant city editor who oversaw breaking news and the courts and entertainment beats.

Earlier, Connor was a staff writer at the New York Post, United Press International and Brooklyn Paper Publications.

Connor has won numerous awards from journalism organizations including the Deadline Club and the New York Press Club.